1. Field of the Invention
The invention relates to a power unit, and more particularly, to a power unit having a power generator connected to an electric load, a first storage device, and a second storage device.
2. Description of the Related Art
Conventionally, there is known a dual power supply vehicle power unit that is equipped with a first battery charged by a power generator driven by an engine and a second battery that feeds a power to an on-vehicle electric load and carries out concerted discharge from both the first battery and the second battery when the first battery does not have a capacity sufficient to drive the electric load alone (e.g., see Japanese Patent No. 4258731).
In the dual power supply vehicle power unit described in Japanese Patent No. 4258731, the first battery is designed to be capable of storing a power regenerated through regenerative braking by the power generator during the braking of a vehicle and then discharging the stored regenerative power to the electric load.
However, in the configuration described in the aforementioned Japanese Patent No. 4258731, when the first battery is fully charged or almost fully charged, it is impossible to sufficiently charge the first battery with a generated regenerative power even when there is an opportunity for regeneration. Thus, an opportunity for regenerative charge, which has the best fuel efficiency, is passed up, and there is caused a problem in that a sufficient regeneration effect cannot be achieved.